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Greenhouse Gases Fluxes from a Drained and Seasonally-Flooded Peatland and a Tidal Wetland

Greenhouse Gases Fluxes from a Drained and Seasonally-Flooded Peatland and a Tidal Wetland. Dennis Baldocchi, Matteo Detto, Joe Verfaillie, Jaclyn Hatala, Oliver Sonnentag UC Berkeley Frank Anderson, USGS/DWR. Bay Delta Science Symposium, Sacramento, Sept 29, 2010.

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Greenhouse Gases Fluxes from a Drained and Seasonally-Flooded Peatland and a Tidal Wetland

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  1. Greenhouse Gases Fluxes from a Drained and Seasonally-Flooded Peatland and a Tidal Wetland Dennis Baldocchi, Matteo Detto, Joe Verfaillie, Jaclyn Hatala, Oliver Sonnentag UC Berkeley Frank Anderson, USGS/DWR Bay Delta Science Symposium, Sacramento, Sept 29, 2010

  2. The Big Picture Science Questions and Problems • Drainage of Delta Peatlands has Caused over 10 m of Soil Subsidence, with Loss due to Respiration and Compaction • Continued Subsidence Strains Levees, making the Water Conveyance System to 20 million people in California Vulnerable to Collapse • Restoring Wetlands Can Sequester Carbon and Re-Build Soils • Carbon Farming Projects are Being Proposed and Implemented • Are there Un-Intended Consequences to Ecological Restoration for Carbon Sequestration? • Flooding can lead to Methane Production and Huge Evaporation in a Region where Water is Scarce and Precious

  3. Objectives • Measure Greenhouse Gas Fluxes, Directly, Quasi-Continuously over Multiple Years with Eddy Covariance and New Generation of Laser Spectrometers • Conduct Greenhouse Gas Flux Measurements Over 3 Contrasting Landscapes • Drained, Peatland Pasture • Seasonally-Flooded Rice Paddy • Remnants of Natural Wetlands

  4. Eddy Covariance Tower Sonic Anemometer, CO2/H2O IRGA, inlet for CH4 Tunable diode laser spectrometer & Meteorological Sensors

  5. Eddy Covariance, Flux Density: mol m-2 s-1 or J m-2 s-1 ESPM 228 Adv Topics Micromet & Biomet

  6. Measuring Methane with Off-Axis Infrared Laser Spectrometer Closed path Moderate Cell Volume, 400 cc Long path length, kilometers High power Use: Sensor, 80 W Pump, 1000 W; 30-50 lpm Low noise: 1 ppb at 1 Hz Stable Calibration Los Gatos Research

  7. Open-Path Laser Spectrometer, LI-7700, for Methane Low Power (8 W) and no pump, Ideal for Use in Remote Locations

  8. Site Locations Drained Peatland Pasture: Sherman Island Seasonally Flooded Peatland: Twitchell Island

  9. P1. Greenhouse Gas Fluxes from Tidal Wetlands Remnants of the Delta before 1850s Sampled from Sherman Island Levee

  10. Methane Emission and CO2 Exchange from Tidal Wetland, Spring 2010

  11. Sherman Island, Drained, Grazed, Peatland Pasture April 2007-Sept, 2010

  12. CO2 Exchange on Sherman Island: April, 2007-August, 2010

  13. Methane Fluxes at Sherman Island Generally Low (~ 10 nmol m-2 s-1) except when Flooded or Cows Pass

  14. P2. Twitchell Island, Seasonally-Flooded Peatland, Rice Paddy

  15. Rice Paddy and USGS Tule Pilot Study, Twitchell Island

  16. Twitchell Island Rice, 2009-2010

  17. All Methane Flux Data

  18. 2009, The First Year of Rice Cultivation <FCH4> = 8.7 +/- 9.8 nmol m-2 s-1 Sherman Island

  19. Why is Methane Efflux relatively Low from the Rice? Water table Depth? shallower will be more mixed and more aerated? Ample Oxygen (~40% of saturation)? Strong Delta winds mix and Circular Pumping aerate water Virgin Land for Rice, relatively depleted surface C pools? Expected peat to be a larger source of C substrate than heavy Clay soils in the Sac Valley Methane Efflux will increase with subsequent cultivation?? Upper layers of soils have been heavily oxidized…

  20. Controls on Methane Efflux Flooding for Rice and Wildlife Mgt Variations in Oxygen in the Water Column

  21. Wetland Vs Pasture Flooding Inhibits Nocturnal Respiration and Daytime Photosynthesis, Compared to the Drained Peatland.

  22. Rice Cultivation vs Grazed Pasture Rice Cultivation Stymies Soil C loss from Delta

  23. Rice Cultivation vs Grazed Pasture Rice Cultivation Evaporates 2X the Water of a Degraded Pasture

  24. Annual Evaporation from Legal Delta at 1 km Resolution Annual ET = 1.37 million acre-ft = 1.69 109 m3/y Map and Model: Y Ryu and D. Baldocchi

  25. Summary • Seasonally Flooded Rice is a Moderate Carbon Dioxide Sink and a weak methane source • This was the first year rice was cultivated on this plot of land • A Drained Peatland Pasture is a Strong Source of Carbon • Plus grazing cows are a strong methane source • Rice Cultivation uses twice as much water as less intensive pasture.

  26. Delta Maps of ET and GPP ET, Delta: 1.38 Million acre-ft per year Product of Youngryel Ryu, D. Baldocchi, Berkeley Biometeorology Lab

  27. Winter Flooding Inhibits Soil CO2 Efflux Preliminary data, sort by wind direction and fix bias in water table

  28. Tide-Methane Flux CoSpectra from Levee

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